Causes of Spoilage:

The spoilage of food takes place due to several factors

which are the causes of spoilage of food.
They are: Water/Moisture (it can act like a medium for
microbial growth), micro-organisms (it causes spoilage
by feeding on the food material and causes
deterioration or decrease of quality in food and also
reduces the nutrient content of the food), packing (due
to improper packing micro-organisms start germinating
on food substances and also decreases the quality and
shelf life or those food products), temperature (if
suitable temperature is not maintained then microbial
growth can occur), improper preparation of food (if the
people preparing the food are infected by microbial
diseases that can spread then it can cause spoilage),
chemical factors (for example if the tip of bananas is
not covered microbes can enter through the tip or
even a cut and spoil the whole banana), physical
factors (if the people preparing or packing the food do
no maintain hygiene by wearing cap, gloves, mask and
apron then their hairs or sweat or dust from their
clothes or can cause spoilage), and insects (insects act
as vectors by spreading micro-organisms).
Classification of foods by Ease of Spoilages:
By the ease of spoilage foods are classified into 3 types:
1)Stable/Non-Perishable Foods: They have long
shelf life nearly 1 year. E.g. - Rice, grains, flour,
sugar and honey.
2)Semi-Perishable Foods: These have less shelf life
when compared with stable foods. E.g. – Potatoes,
onions and apples.
3)Perishable Foods: This type of foods does not have
long shelf life. E.g. – Meat, poultry, fish, and leafy
vegetables.
Chemical Changes Caused by Micro-organisms:
Microbes can cause many chemical changes in foods.
For example,
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W h ich e ff e c ts o u r liv e r th e n sto m a ch th e n sm a ll in te sti n e a n d a t la st la rg e in te sti n e

Contamination and Spoilage of Foods:

Foods that are tainted because they either contain
microorganisms, such as bacteria or fungus, or toxic
substances that make them unfit for consumption is
called contamination or spoilage of foods.
Milk and Milk Products:
Bovine milk is typical of other milk types and it is the
basis of the discussion.
The protein content of milk is considerably lower (3.5
vs. 18.0%) while the carbohydrate content is
considerably higher (14.9 vs. ca. 1.0%)
The average water content near the surface of milk is
87% .
Milk protein consists mainly of casein, and it exists in
several classes: α, β, etc. If milk pH falls below 4.6, the
casein precipitates. Although casein represents 80–
85% of total milk protein, when precipitation occurs,
the liquid portion is referred to as whey. The remaining
proteins are found in whey and they include serum
albumin, immunoglobulins, α-lactalbumin, etc. Milk
carbohydrate is principally lactose
Although lactose is the main sugar, smaller quantities
of glucose and citric acid exist. The fat content varies
between ca. 3.5 and 5.0% depending upon cattle
breed, and it consists mainly of triglycerides composed
of C14, C16, C18, and C18:1 fatty acids. Smaller
quantities of di-glycerides and phospholipids occur.
Milk lipids exist largely in the form of fat globules that
are surrounded by a phospholipid layer. The ash
content of around 0.7% consists of a relatively high
level of Ca2+ and a lower level of Fe2+. Overall, the
non-fat solids in cow’s milk average ca. 9.0% while
total solids range between 12.5 and 14.5%, and
average ca. 12.9% depending upon breed.
As the only natural source of the disaccharide lactose,
milk undergoes microbial spoilage in a way that is
unique. Only a relatively small number of milk-borne
bacteria can obtain energy from this sugar (especially
at refrigerator temperatures)
The bacterial spoilage of either raw or pasteurized milk
is conspicuous by the production of lactic acid by
lactose users, with the normal pH of around 6.6 being
reduced to 4.5 or so that leads to the precipitation of
casein (curdling).
Milk is processed in a number of ways to produce a
variety of products
Milk Products:
For milk products such as cream, cheese, and butter
whole fresh milk is processed.
Skim milk (0.5% fat) or reduced fat milk (up to 2.0%
fat) is produced by high-speed centrifugation following
heating to ca. 100◦F to remove butter fat as cream, or
by use of skim milk to which the desired fat content is
added.
Evaporated milk is produced by the removal of about
60% water from whole milk which results in the lactose
content being about 11.5%. Sweetened condensed
milk is produced by the addition of sucrose or glucose
before evaporation. This leads to a product with a
sugar content of about 54% or >64% in solution.
Chocolate milk is processed at a slightly higher
temperature than unflavoured milk (75◦C for 15 sec
rather than 72◦C). A study of chocolate milk from four
plants revealed that the APC was higher at 14 days
post-processing than unflavoured milk even though the
initial numbers for both types were essentially the
same
Some of the other dairy products include butter, sweet
cream, sour cream, ghee, cheese (Swiss cheese,
mozzarella cheese and cheddar cheese), cottage
cheese (also known as paneer).

Fruits and Vegetable Products:

Fruits:
The general composition of fruits, average water
content is about 85%, and the average carbohydrate
content is about 13%. The fruits differ from vegetables
in having somewhat less water but more carbohydrate.
The mean protein, fat, and ash content of fruits are,
respectively, 0.9%, 0.5%, and 0.5% somewhat lower
than vegetables except for ash content. Fruits contain
vitamins and other organic compounds.
In common usage, products such as tomatoes and
cucumbers are referred to as vegetables and yet from
the botanical standpoint they are fruits. Lemons,
oranges, and limes are fruits botanically as well as in
common usage
The pH of fruits is below the level that generally
favours bacterial growth. The wider pH growth range
of moulds and yeasts suits them as spoilage agents of
fruits. With the exception of pears, which sometimes
undergo Erwinia rot, bacteria are of no known
importance in the initiation of fruit spoilage.
Fruit Products:
Fruit products include Fruits juices, Fruit milk shakes,
varieties of fruit jam, and different kinds of jellies.
Vegetables:
The average water content of vegetables is about 88%,
with an average content of 8.6% carbohydrates, 1.9%
proteins, 0.3% fat, and 0.84% ash. The total percentage
composition of vitamins, nucleic acids, and other plant
constituents is generally less than 1%.
Vegetables contain higher water content than fruits.
Vegetables contain vitamins and other organic
compounds.
Vegetable Spoilage:
The incidence of microorganisms in vegetables may be
expected to reflect the sanitary quality of the
processing steps and the microbiological condition of
the raw product at the time of processing.
Numbers of bacteria that have been reported for a
number of different fresh vegetables
General build-up of staphylococci occurred as the
vegetables underwent successive stages of processing,
with the main source of organisms coming from the
hands of employees. Although staphylococci may be
found on vegetables during processing, they are
generally unable to proliferate in the presence of the
normal lactic biota.
This is precisely the case; some of the most ubiquitous
etiologic agents in the bacterial spoilage of vegetables
are species of the genera Erwinia and Pectobacterium,
and they are associated with plants and vegetables in
their natural growth environment. The common
spoilage pattern displayed by these organisms is
referred to as bacterial soft rot.
Vegetable products:
Tomato puree, ginger garlic paste, pumpkin flakes, red
and green chilli sauce, tomato sauce and paprika are
some of the vegetable products.
Meat and Poulty:
Meat:
Some of the examples of the meat consumed by
humans are as follows: Buffalo, cow, goat, horse, and
rabbit.
Animals go through stunning (shocks) process after
which the animals are unconscious then they are taken
to cut into pieces.
Meat is generally of 2 types:
1. Fresh and Refrigerated Meat:
In this type if spoilage occurs the microorganisms
found are Acinetobacter, Moraxella, Pseudomona,
Aeromonas, molds, and yeast etc.
2. Processed and Cured/Stored Meat:
 In this type of meat if spoilage occurs
microorganisms found in meat are lactobacillus,
other lactic acid bacteria, molds (aspergillus,
penicillium, rhizopus), and yeast (torula,
debaryomycesi, canelida).
Preservation of Meat:
There are several methods to preserve meat from
spoilage.
1)Heat/ Smoked method: In this method meat is
hanged and then smoke is supplied to it.
2)Chilling method: In this process ice is used to keep
the meat cool in order to preserve it.
3)Freezing/ Curing method: Some chemicals like
sodium chloride, sodium nitrite, sodium nitrate
and table sugar is used to store the meat in
freezer.
4)Dry method: In this method meat is cut into pieces
and dried in sun heat due to which the moisture in
it evaporates and thus it is preserved.
5)Spices: In this method meat is marinated with
some spices due to which it is preserved for long
time.
 6)Antibiotics: Antibiotics such as Nasin,
chloramphenol, oxytetracycline, and
chlortetracycline are used to preserve meat.
Symptoms of Spoilage of meat:
Meat exhibits several symptoms when spoilage
occurs like: Stickiness (sticky/gummy nature),
whiskers (white foam like formation), black spot
(black spot formation occurs), white spot (white spot
formation occurs), Green patches (formation of
green patches takes place), off-tasty (bad taste),
souring (sour taste), Bitter (taste of meat will
become bitter).
Fish:
Fishes are beaten with a rod before killing them to
make them unconscious. If the fish taken to eat is
spoiled it omega 3 fatty acids present in it can
transform into poison.
Poultry:
Meat and egg derived from birds is called poultry.
Meat is derived from a bird by injecting it with some
drugs due to which the hen will be unconscious. Then it
is taken to be cut into pieces with a cutter. If the bird
that has been cut has any infection or disease then the
meat can have the chances of getting spoiled. If such
spoiled poultry food is consumed then it may cause
health problems like early maturation in girls with
more bleeding.
Grains and Oil Seeds:
Grains: Some of the examples of grains include cereals
and pulses like rice, wheat, corn, barley, etc.
If spoilage occurs in grains there is only a slight change
in taste and also deterioration occurs. Other than that
there is no big difference.
In industries, some of the common micro-organisms
infecting grains are pseulomonadaceae, microccaceae,
lactobacillaecae, bacilaceae, coliform, microccus,
serratia, fungus (penicillia).
Oil Seeds: Some examples of the oil seeds are ground
nuts, mustard, sesame, castor, etc.
If spoilage occurs in oil seeds they taste bitter and also
deterioration occurs in them.
Factors for the spoilage of Grains and Oil seeds:
1. Moisture: Food can spoil due to moisture that can
come from sweaty workers, rain, wet hands of
workers, etc.
2. Temperature: If room temperature is not
maintained then moisture formation occurs which
can result in spoilage.
3. Packaging:
4. pH value:
5. Preservatives: